One reason that the Empire expanded under Justinian was because of his ability to pick exceptional advisors. The men that he gave power to owed this to him and so were very loyal. Despite many periods of financial and military crisis where the Empire faced threats from all sides it always managed to come through, often due to the talents of the Emperors advisors. One of the talented generals during Justinian’s reign was Belisarius. Belisarius was a former member of Justinian’s bodyguard whom the Emperor saw potential in. The general was with Justinian for much of his reign and had many victories against larger enemies. In 530, near the border fortress of Dara, he defeated a much larger Persian force, showing his talents as a commander. He was also in charge of the force that reconquered Africa by the end of 533, less than a year after he landed with an army of around 18,000 soldiers.
Another reason that the Byzantine Empire expanded in power under Justinian was the reconquest of North Africa and Italy. Having these two areas under its control meant that the Mediterranean was once again a Roman sea and the trade that was now available to the Empire would greatly increase its revenue. These two former Roman territories were still very important to the Eastern Empire. The conquest of Africa in 533 by Belisarius also increased the wealth of the Empire as the general took back the Vandal treasury, once plundered from the Romans. The mere fact that these two areas were back under Roman control, especially Italy as the home of the former capital of Rome, would have greatly increased Byzantium prestige among the other nations of
Bibliography: Diehl, Charles. History of the Byzantine Empire. Princeton University Press, 1945 Downey, Glanville. Justinian as a Builder. http://www.jstor.org/stable/select/3047311 Hussey, J.M. The Byzantine World. Hutchinson and Co Ltd, 1967 Treadgold, W.A. A History of the Byzantine State and Society. Stanford University Press, 1997